A critical decision confronting health care providers is how to predict in the acute setting which children will suffer persistent postconcussive symptoms (PCS) and functional impairments after mild traumatic brain injury (TBI). Mild TBI occur in >450,000 youth under 15 years of age annually and can result in persistent symptoms associated with significant functional impairments. Various methods are recommended for the diagnostic evaluation of children with mild TBI: assessment of presenting signs/symptoms, acute mental status examination and balance testing, neuropsychological testing, and neuroimaging. However, no previous study has systematically compared the prognostic significance of these methods. The overall goal of the proposed project is to examine the utility of diagnostic methods commonly used in clinical settings in the prediction of persistent PCS and functional impairments. Participants will include 8- to 15-year-old children with mild TBI (n = 200) or mild orthopedic injuries (n = 100), recruited in the Emergency Departments (ED) at two large children's hospitals. Acute signs and symptoms of concussion, as well as mental status and balance, will be assessed using standardized methods at the time of recruitment. All children will complete computerized neuropsychological testing and magnetic resonance imaging (MRI) within 7 days of injury. PCS will be assessed remotely on a weekly basis using electronic devices during the first 6 months post injury. Functional impairments will be assessed in person acutely and 3 and 6 months post injury. Other potential confounds (e.g., children's premorbid functioning; effort; pain; symptom exaggeration) also will be assessed. The proposed research is innovative because no previous study has compared the predictive utility of these commonly-used methods for assessing pediatric mild TBI. Additional innovations include collecting ratings of PCS at home on electronic devices to obtain real-time data from participants; assessing balance using a simple measure commonly employed in sports concussion research but not yet studied in a broad sample of children with mild TBI; using a newly-developed, computerized neuropsychological test battery to assess cognitive abilities; and employing newer MRI sequences capable of detecting subtle abnormalities (i.e., SWI, DTI). Our specific aims are (1) to examine the prediction of PCS and functional impairments following mild TBI and (2) to determine the incremental predictive utility of each of four assessment methods. Statistical analyses will assess the independent and combined contributions of four sets of variables to the prediction of PCS and functional impairments: (a) presenting signs/symptoms; (b) acute mental status and balance testing; (c) neuropsychological testing; and (d) neuroimaging. Prediction will be evaluated using mixed models, as well as traditional indices of clinical utility. A comprehensive study of these diagnostic methods and their incremental utility in predicting outcomes will have a major impact on clinical practice, particularly in acute care settings, by helping improve prognostic determinations, develop decision tools, and focus treatment efforts.